I heard a point, that all (human) body atoms are recycled withing short period like few years. Recycled means "old" atoms are replaced by "new" ones during metabolism, leaving only structure unchanged.

But this looks contradicting with knowledge about DNA. DNA molecule looks unchanged and the fate of all it's atoms looks known.

Yes I know there are some spontaneous damages which are repaired, but most of DNA atoms remain in place. Even during cell division, 50% of atoms goes to one of the descendant cells. I.e. they don't go outisde body.

So, if the point is wrong concerning DNA atoms, then may it is wrong at all?

3 Answers
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This technique, which may be dated to the discovery of deuterium by Urey in 1933, produced a revolution in biological thought.

Much of the early work was done at the Department of Biological Chemistry at Columbia University under the chairmanship of H. T. Clark.

Up to this time it was thought that the components of tissues were relatively stable, and that ingested food was metabolized immediately to provide a source of energy.

The first experiments showed that when deuterated fatty acids were fed to mice, most of the label was initially deposited in adipose tissue.

It was concluded that adipose tissue acts a 'fuel depot' that is in a state of metabolic flux and is the direct source of fatty acids burned as a fuel (see here for refs). Fats present in food are not primarily used an an immediate energy source.

When a stable isotope of nitrogen became available (N15), it was found that proteins were also 'in a state of dynamic flux' and were being continuously regenerated and broken down.

Further information about the early work on isotopes, their role in changing completely the way we think about metabolism, and the role of Columbia University in shepherding in this great era, may be found in the following open-access article by Eugene. P. Kennedy:

In the original answer I said that the original isotope experiments were done with radioactive fatty acids. This, of course, is rubbish. They were done with deuterated fatty acids.
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TomDNov 1 '13 at 11:09

I think you're right. DNA contradicts the notion of "total mass turnover." So the point is not generally correct. Of course, how incorrect the statement is reflected by the mass ratio of DNA to non-DNA components -- most all of those other components do turn over multiple times in a lifespan (including things that seem frozen-out like bone calcium).

But how do we know that other atoms are turned over? May be ribosome or cytoskeleton proteins are also persist?
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Suzan CiocOct 30 '13 at 20:31

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Are you asking, what experimental techniques monitor the turnover of biochemicals? Whole-animal metabolic studies are the main historic source of these kinds of statements. Let's say you give a mouse 14C-labeled food for its first six months of life, then switch it to unlabeled food. Monitoring the whole-mouse 14C content over time lets you quantify turnover.
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RyanOct 30 '13 at 21:33

Y'all are neglecting the fact that cells die and are continually replaced, which would include replicating the DNA with new atoms. The most interesting study I've seen on this is summarized in this New York Times article. Above ground nuclear testing up until 1963 released a great deal of Carbon-14 into the atmosphere. This ultimately became incorporated into the DNA of anyone living at the time, and was used as a marker for how quickly specific tissues turned over in the body.